Who is responsible for the development unit, property management company and heating company?

The heating company should be responsible for this incident.

According to the Property Management Law, central heating in residential quarters belongs to heaters, which provide maintenance, management and repair for equipment and facilities. Entrusted property management, the property is responsible for. I'm afraid it's too long to write down the specific laws and regulations here, but I can tell the landlord that the responsible party has been clearly defined in the laws and regulations, regardless of whether there is any other connection between them, as long as either you or he is responsible.

For details, please refer to Chapter 6, Housing Equipment Management, Section 5, Heating Equipment Management of Introduction to Property Management.